1. Field of the Invention
This invention relates to conveyor belt systems, and more particularly to self-stacking, spiral conveyor belt systems.
2. Description of the Related Art
There is shown in FIGS. 1-3, a self-stacking conveyor belt system used in the prior art. Such systems include a continuous belt coupled to a drive system (not shown) that causes the belt to form a compact spiral (also called a spiral configuration herein) generally indicated by the reference number. The continuous belt is made of interconnecting links that allow the belt to continuously move in a straight path and then wrap around a rigid guide ring, generally indicated by the reference number, to form the spiral. Various types of belts and drive assemblies are disclosed in the following twelve (12) U.S. Pat. Nos. 3,938,651; 4,564,282; 4,850,475; 4,858,750; 4,899,871; 5,105,934; 5,247,810; 5,277,301; 5,350,056; 5,458,228; 5,460,260; and 6,062,375 that are now incorporated by reference herein.
The guide ring widely used in the prior art is a cylindrical structure approximately 12 to 24 inches in height and 60 to 84 inches in diameter. The spiral is approximately 4 to 36 inches higher than the guide ring. Because the guide ring is shorter than the spiral, the upper tiers of the belt located above the guide ring are unsupported centrally. As a result, forces exerted on the belt and the unsupported upper tiers to automatically stack in an offset position towards the guide ring's center axis. Because the forces exerted on the unsupported upper tiers are relatively large, the distance the upper tiers are offset over the lower tiers is relatively large which, in turn, causes the inner belt spacers on the links located on the lower tiers to bend. When the amount of bend exceeds the fatigue limits of the spacers, cracks are created which eventually lead to breakage.
It is an object of this invention to provide an improved guide ring used with a spiral conveyor belt self-stacking drive system that reduces the stress on the links and thus breakage.